A METHOD TO DEINK PLASTIC MATERIAL

Abstract

This disclosure relates to a method to deink plastic material comprising or provided with ink. The method comprises the step of contacting the plastic material with an oxidizing inorganic acid having a standard electrode potential of at least 0 V. The disclosure also relates to a method to delaminate and deink plastic material by contacting the plastic material with an oxidizing inorganic acid and with a short chain or medium chain fatty acid. Furthermore, the disclosure relates to an installation to deink or to delaminate and deink plastic material.

Claims

1. A method to deink plastic material, the method comprising the steps of providing plastic material comprising or provided with an ink selected from the group consisting of nitrocellulose based resins, polyurethane based resins, polyvinylchloride based resins, ethyl cellulose based resins, cellulose acetate propionate based resins, cellulose acetate butyrate based resins, polyvinyl butyral based resins, acrylate based resins, polyacrylate based resins, polyamide based resins, maleics based resins, modified rosin based resins, alkyd based resins and any combination thereof; contacting the plastic material with an oxidizing inorganic acid having a standard electrode potential of at least 0 V; and separating the thus obtained plastic material from the oxidizing inorganic acid.

2. The method according to claim 1, wherein shear is applied to the plastic material before or while contacting the plastic material with the oxidizing inorganic acid.

3. The method according to claim 1, wherein the plastic material is reduced in size to obtain plastic material having a sieve diameter ranging between 0.01 cm and 20 cm before being contacting the plastic material with the oxidizing inorganic acid.

4. The method according to claim 1, wherein during the contacting of the plastic material with the oxidizing inorganic acid the volume of plastic material over the volume of the oxidizing inorganic acid ranges between 0.1 and 10.

5. The method according to claim 1, wherein the oxidizing inorganic acid comprises an oxyacid.

6. The method according to claim 1, wherein the oxidizing inorganic acid is selected from the group consisting of HNO.sub.3, H.sub.2SO.sub.4, HClO.sub.4, H.sub.2CrO.sub.4, H.sub.2SeO.sub.4, HMnO.sub.4, HTcO.sub.4, HReO.sub.4, H.sub.3PO.sub.4, H.sub.3AsO.sub.4, H.sub.2TeO.sub.4, HBrO.sub.4 and HIO.sub.4.

7. The method according to claim 1, wherein the oxidizing inorganic acid contacting the plastic material is present in a concentration of at least 20 wt %.

8. The method according to claim 1, wherein the plastic material is contacted with the oxidizing inorganic acid at a temperature of at least 20° C.

9. The method according to claim 1, wherein the method further comprises the step of contacting the plastic material with a fatty acid, the fatty acid being a short chain fatty acid having less than 6 carbon atoms or a medium chain fatty acid having 6 until 12 carbon atoms; and optionally, separating the obtained plastic material from the fatty acid, whereby the step of contacting the plastic material with the fatty acid is applied either before the step of contacting the plastic material with the oxidizing inorganic acid or after the separation of the plastic material from the oxidizing inorganic acid.

10. The method according to claim 9, wherein during the contacting of the plastic material with the fatty acid the volume of plastic material over the volume of the fatty acid is at least 0.001.

11. The method according to claim 9, wherein the short chain fatty acid is selected from the group consisting of formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid and the medium chain fatty acid is selected from the group consisting of caproic acid, caprylic acid, capric acid and lauric acid.

12. The method according to claim 9, wherein the short chain fatty acid or the medium chain fatty acid contacting the plastic material is present in a concentration of at least 20 wt %.

13. The method according to claim 9, wherein the plastic material is contacted with the fatty acid at a temperature of at least 20° C.

14. The method according to claim 9, wherein the plastic material comprises monolayer and/or multilayer plastic material.

15. (canceled)

16. The method according to claim 10, wherein the short chain fatty acid is selected from the group consisting of formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, and the medium chain fatty acid is selected from the group consisting of caproic acid, caprylic acid, capric acid, and lauric acid.

17. The method according to claim 10, wherein the short chain fatty acid or the medium chain fatty acid contacting the plastic material is present in a concentration of at least 20 wt %.

18. The method according to claim 11, wherein the short chain fatty acid or the medium chain fatty acid contacting the plastic material is present in a concentration of at least 20 wt %.

19. The method according to claim 16, wherein the short chain fatty acid or the medium chain fatty acid contacting the plastic material is present in a concentration of at least 20 wt %.

20. The method according to claim 10, wherein the plastic material is contacted with the fatty acid at a temperature of at least 20° C.

21. The method according to claim 11, wherein the plastic material is contacted with the fatty acid at a temperature of at least 20° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0161] This disclosure will be discussed in more detail below, with reference to the attached drawings, in which:

[0162] FIG. 1A shows the deinking rate of different types of plastic packaging films after treatment using a method according to this disclosure using sulfuric acid with a time span of 0 until 300 seconds;

[0163] FIG. 1B shows a detail of FIG. 1A with a time span of 0 until 30 seconds;

[0164] FIG. 2 shows the deinking rate of different types of plastic packaging films after treatment using a method using ethyl acetate;

[0165] FIG. 3 shows the deinking rate of different types of plastic packaging films after treatment using a method using cetrimonium bromide (hexadecytrimethylammoniumbromid) (CTAB);

[0166] FIG. 4 shows the saturation point of three different tested deinking methods; and

[0167] FIG. 5 shows the deinking time using different ratios of volume of plastic over the volume of the oxidizing inorganic acid (referred to as washing medium) at the following conditions: 55% H.sub.2SO.sub.4 as deinking medium, in a batch reactor with volume of 1 L, stirred with an agitator at 600 rpm, at 25° C.

DETAILED DESCRIPTION

[0168] This disclosure will be described with respect to particular embodiments and with reference to certain drawings but the disclosure is not limited thereto but only by the claims. The drawings are only schematic and are non-limiting. The size of some of the elements in the drawing may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the disclosure.

[0169] When referring to the endpoints of a range, the endpoints values of the range are included.

[0170] When describing the disclosure, the terms used are construed in accordance with the following definitions, unless indicated otherwise.

[0171] The term ‘and/or’ when listing two or more items, means that any one of the listed items can by employed by itself or that any combination of two or more of the listed items can be employed.

[0172] The terms ‘first,’ ‘second’ and the like used in the description as well as in the claims, are used to distinguish between similar elements and not necessarily describe a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the disclosure described herein are capable of operation in other sequences than described or illustrated herein.

EXAMPLES AND EXPERIMENTAL RESULTS

Example 1

[0173] A multilayer plastic packaging film comprising a PET layer, a solvent-based ink, a polyurethane-based adhesive, and a white PE layer, in this sequence, was reduced in size by a shredder with a sieve diameter of 2.38 mm. The obtained particles were brought into contact with formic acid under continuous stirring with an agitator at 500 rpm. The formic acid has a concentration of 99.9 w/w %. The volume of the plastic material over the volume of formic acid was 0.001. 100% delamination was obtained in 20 seconds. The delamination percentage was measured by quantifying the absorbance of some defined peaks of the present tie layer. Thereafter, the delaminated polymers were deinked through interaction with sulfuric acid at 70° C. under continuous stirring with an agitator at 350 rpm. The volume of the plastic material over the volume of sulfuric acid was 0.1. The sulfuric acid has a concentration of 96.0 w/w %. 100% deinking was obtained in 5 seconds. The deinking percentage was measured via an optical-based technique, quantifying the optical density of the sample.

Example 2

[0174] A plastic packaging film comprising a transparent oriented polypropylene (OPP) layer, a nitrocellulose/polyurethane resin, and a solvent-based black ink layer, respectively, was reduced in size by a shredder with a sieve diameter of 2.38 mm. The obtained particles were brought into contact with sulfuric acid at 70° C. under continuous stirring with an agitator at 250 rpm. The volume of the plastic material over the volume of sulfuric acid was 0.1. The sulfuric acid has a concentration of 80 w/w %. 100% deinking was obtained in 90 seconds.

Example 3

[0175] A multilayer plastic packaging film comprising a PET layer, a solvent-based ink, a polyurethane-based adhesive, an aluminum layer, another polyurethane-based adhesive, and a PP layer in this sequence, was reduced in size by a shredder with a sieve diameter of 2.38 mm. The obtained particles were brought into contact with formic acid at 100° C. under continuous stirring with an agitator at 100 rpm. The formic acid has a concentration of 75 w/w %. The volume of the plastic material over the volume of formic acid was 0.001. 100% delamination was obtained in 100 seconds. Thereafter, these delaminated polymers can be deinked with an oxidizing inorganic acid, as disclosed in this disclosure.

Example 4

[0176] A plastic packaging film comprising a transparent OPP substrate, a cross-linked acrylate resin, a UV-based white ink layer, and a cyan ink layer as top layer, was reduced in size by a shredder with a sieve diameter of 2.38 mm. The obtained particles were brought into contact with sulfuric acid at 25° C. under continuous stirring with an agitator at 250 rpm. The volume of the plastic material over the volume of sulfuric acid was 0.1. The sulfuric acid has a concentration of 96.0 w/w %. 100% deinking was obtained in 45 seconds.

Example 5

[0177] A plastic packaging film comprising a PE layer, an ethylene vinyl alcohol (EVOH) layer, a PET layer, and a water-based red ink layer, in this sequence, was reduced in size by a shredder with a sieve diameter of 20 mm. The obtained particles were brought into contact with nitric acid at 25° C. under continuous stirring with an agitator at 250 rpm. The volume of the plastic material over the volume of nitric acid was 0.1. The nitric acid has a concentration of 70.0 w/w %. 100% deinking was obtained in 300 seconds.

[0178] Comparison of the Method According to this Disclosure with Existing Deinking Processes

[0179] The deinking rate of 7 different types of plastic packaging materials (referred to as plastic 1 to plastic 7) using three different deinking methods (referred to as method A to C) is compared.

[0180] The composition of the 7 types of plastic packaging material (type of ink, resin, substrate and varnish) is described below.

[0181] The tested plastic packaging materials comprise: [0182] 1 PE films with solvent-based cyan ink and a varnish layer [0183] 2 PE film with solvent-based black ink [0184] 3 OPP film with solvent-based white ink, cyan ink and a varnish layer [0185] 4 OPP film with water-based cyan ink [0186] 5 OPP film with water-based white ink and cyan ink [0187] 6 OPP film with UV-based cyan ink [0188] 7 OPP film with UV-based cyan ink and a varnish layer

[0189] The three different deinking methods are described below: [0190] Method A comprises a method according to this disclosure in which the plastic packaging material is brought in contact with sulfuric acid (concentration 96.0 w/w %) at 70° C. under continuous stirring with an agitator at 250 rpm. [0191] Method B the plastic is brought in contact with ethyl acetate (concentration 99.8 w/w %) at 77° C. under continuous stirring with an agitator at 250 rpm. [0192] Method C the plastic is brought in contact with a surfactant, in this case cetrimonium bromide (CTAB) with a concentration of 10 mM at 80° C. under continuous stirring with an agitator at 250 rpm.

[0193] Method B and Method C are methods known in the prior art as deinking methods, respectively described in DE19651571A1 and EP2832459A1.

[0194] The deinking rates of the different packaging materials of method A are shown in FIG. 1A (with a time span of 0 until 300 seconds) and FIG. 1B (with a time span of 0 until 30 seconds). The deinking rates of the different packaging materials of method B and method C are respectively shown in FIG. 2 (with a time span of 0 until 600 seconds) and FIG. 3 (with a time span of 0 until 1200 seconds).

[0195] A comparison of the three deinking methods shows that only the method according to this disclosure (Method A, using sulfuric acid, as an oxidizing inorganic acid) is able to deink all types of plastic films. Moreover, the method according to this disclosure (Method A) deinks all types of films faster compared to the other deinking methods.

[0196] FIG. 4 indicates the saturation points of the three tested deinking methods, measured by determining the amount of fully printed films with a size of 2.8 cm×3.5 cm that could be deinked completely in 100 mL of liquid medium. The results show that sulfuric acid has a much higher saturation point compared to ethyl acetate and CTAB. While with ethyl acetate (at a concentration of 99.5 w/w %, a temperature of 77° C., and an agitation speed of 250 RPM) and CTAB (at a concentration of 0.009 mol/L (=10×CMC), a temperature of 25° C., and an agitation speed of 250 RPM) less than 0.5 cm.sup.2 of a fully printed monolayer packaging film can be deinked per mL of solvent, with sulfuric acid (at a concentration of 96.0 w/w %, a temperature of 70° C., and an agitation speed of 200 RPM) around 30 cm.sup.2 of a fully printed monolayer packaging film per mL can be deinked.

[0197] FIG. 5 shows the deinking time using different ratios of volume of plastic over the volume of the oxidizing inorganic acid (referred to as washing medium) at the following conditions: 55% H.sub.2SO.sub.4 as deinking medium, in a batch reactor with volume of 1 L, stirred with an agitator at 600 rpm, at 25° C. The deinking time was determined by visual inspection and using video-based analysis.